Large mail processing facilities, such as letter shops, captive shops and service bureaus use high speed inserters which run at up 22,000 mail pieces per hour. The mailpieces come out of the inserter onto a stacking belt. Individual trays are marked with an edge marker or the first or last mailpiece is offset on the stacker belt. An operator must identify the tray visually and sweep the mail from the stacker belt and place the mailpieces in a mail tray. Since a tray holds approximately 350 mailpieces, the operator will often need to make several sweeps to fill a tray. This process is slow and can introduce errors if the trays are not maintained accurately due to sweeping errors caused by missing the edge mark or disturbing the mail stacked on the belt. Disturbance of the stack can result in losing the offset mailpiece indication for the end or beginning of a tray. The operator is also required to insert the correct tray tag in each mail tray. The stacker belt provides some buffer for the operator but he must average at least a tray per minute. If the operator falls behind, the inserter may have to be stopped, which impacts throughput. A similar problem exits for high speed printers that produce mailpieces such as postcards or self mailers since the output must be correctly swept into trays.
There are significant penalties for not keeping the mailpieces in a tray group together. If mailpieces are in the wrong tray or an incorrect tag is placed on the tray, presort postage discounts maybe lost for the mailing. In addition, no verification is made to ensure that all of the mailpieces have been manufactured and put in the correct tray group. As a result the mailing documentation maybe incorrect and not represent the actual mailing to be provided to the postal authority.
The mail pieces from the inserter or printer can be run on a sorter provided there is a sorter with sufficient sort bins available to meet the presort requirements. Sort schemes to control the sortation process also need to be developed based on the jobs to be run. Generating sort schemes is a highly manual process based on experience or documentation defining the delivery points associated with the mailpieces in the job to be run. Also, depending on the sort scheme and mail makeup, a second pass through the sorter maybe required to meet presort rules for discounted postage.
Hence a need exists for a mail sorter that can process the mail that is manufactured by an inserter or printer. This sorter system sort the mailpieces without a predefined sort scheme and will correct any errors in the grouping of mail pieces in mail trays in accordance with presort groups. In addition, the sorter will verify that all of the mailpieces that were manufactured are accounted for and update the mailing documentation for any discrepancies. These operations can be performed at 40 to 50 thousand mailpieces per hour on a sorter. Another advantage for the sorting approach is throughput gains. The sorter requires a few minutes of setup between jobs since the sort scheme is setup automatically during sortation. Sweeping of the sorter bins is more efficient since fewer bins are used and they a grouped in one area to facilitate sweeping with minimum movement by the operator. One sorter can service multiple inserters or printers and ensure the job accuracy demanded by the postal authority and clients.